Troubleshooting Switched Networks 85
Complete these steps to solve this problem:
Step 1 Temporarily change the VTP mode to transparent.
Step 2 Add the VLAN to which the uplink port is assigned to the VLAN
database.
Step 3 Change the VTP mode back to client after the uplink port begins
forwarding.
Troubleshooting Spanning Tree
It is also important to know how to identify and resolve spanning-tree issues, assuming port
connectivity, VLAN, and VTP problems have been identi?¬?ed and resolved. Figure 2-41
shows the ?¬‚ow for troubleshooting STP.
Figure 2-41 Troubleshooting STP
Use the Diagram of the Network
Before you troubleshoot a bridging loop, you must at least be aware of the following:
?– The topology of the bridge network
?– The location of the root bridge
?– The location of the blocked ports and the redundant links
Troubleshoot
Physical Layer
Port Connectivity
Issues
Troubleshoot
VLAN
Issues
Troubleshoot
VTP/Trunking
Issues
Troubleshoot
Spanning-Tree
Issues
Use
Network Diagram
to ID Root and
Blocked Ports
Identify
Bridging Loop
and Restore
Connectivity
Quickly
Check STP
Log Events
Verify Root
Bridge Selection
and That RSTP
Is Enabled
86 Chapter 2: Medium-Sized Switched Network Construction
This knowledge is essential for the following reasons:
?– Before you can determine what to ?¬?x in the network, you must know how the network
looks when it is functioning correctly.
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